With the continued concern over global climate change there is an increasing need to develop technologies to replace those with high ozone depletion potential (ODP) and high global warming potential (GWP). Though hydrofluorocarbons (HFC), being non-ozone depleting compounds, have been identified as alternative blowing agents to chlorofluorocarbons (CFCs) and hydrochlorofinomearbons (HCFCs) in the production of thermoplastic foams, they still tend to have significant GWP.
Hydrofloroolefins, such as HFO-1243zf, (cis/trans)-HFO-1234ze, HFO-1234yf, and (E/Z)-HFO-1225ye, have been identified as potential low GWP blowing agents for the production of thermoplastic foams, including extruded polystyrene foams for thermal insulation.
It was discovered that blowing agent compositions comprising at least one hydrofluoroolefin with at least one hydrochlorofluoroolefin can permit the production of lower density, closed-cell foam with good k-factor which will be particularly useful for thermal insulating foams. This invention may also permit the production of low density, closed-cell foams with enlarged, controlled cell size.
WO 2004/037913, WO 2007/002703, and US Pat. Publication 2004119047 disclose blowing agents comprising halogenated alkenes of generic formula that would include numerous HFOs and HCFOs, among many other materials including brominated and iodinated compounds. The specific combination of HFOs with HCFOs in blowing agent compositions is not disclosed. Specific examples are shown for blowing agent compositions for foaming polystyrene comprising HFOs, specifically HFO-1234ze and HFO-1234yf, either alone or in combination with an HFC, and blowing agent compositions for PUR foaming comprising HCFO-1233zd. No examples of blowing agents combinations comprising HFOs and HCFOs are disclosed.
GB 950,876 discloses a process for the production of polyurethane foams. It discloses that any suitable halogenated saturated or unsaturated hydrocarbon having a boiling point below 150° C., preferably below 50° C., can be used as the blowing agent. Trichlorofluoroethene, chlorotrifluoroethene, and 1,1-dichloro-2,2-difluoroethene are disclosed in a list of suitable blowing agents along with 3,3,3-trifluoropropene. Hydrochlorofluoropropenes are not specifically disclosed nor are longer chain HCFOs nor other HFOs besides 3,3,3-trifluoropropene. There is no disclosure related to blowing agents for thermoplastic foaming, nor are the benefits of HCFOs in thermoplastic foaming mentioned, nor are the benefits of blowing agent combinations comprising HCFOs and HFOs.
CA 2016328 discloses a process for preparing closed-cell, polyisocyanate foam. Disclosed are organic compound blowing agents including halogenated alkanes and alkenes, where the alkene is propylene, and the halogenated hydrocarbons can be chlorofluorocarbons. Among the many exemplary compounds listed are specific chlorofluoroethylenes containing 1 chlorine and from 1 to 3 fluorines along with specific pentafluoropropene, tetrafluoropropene, and difluoropropene. Hydrochlorofluoropropenes are not specifically disclosed nor are longer chain HCFOs. There is no disclosure related to blowing agents for thermoplastic foaming, nor are the benefits of HCFOs in thermoplastic foaming mentioned, nor are the benefits of blowing agent combinations comprising HCFOs and HFOs.